1. Field of the Invention
This invention relates to the field of synthetic alcohols and to products useful for forming synthetic surfactants. Novel compositions exhibiting unusual characteristics and superior properties are included.
2. Description of the Prior Art.
Alcohols derived from both natural and synthetic origins have been widely utilized in a variety of applications. Exemplary areas in which such alcohols and their derivatives have been employed include their application in plasticizers, textile treatments, lubricants, polyurethanes, amines, alkyd coatings, surfactants, and the like. The employment of alcohols in the surfactant area is notably increasing in importance.
Surfactants, such as the alcohol alkoxylates, have been broadly employed by the detergent and other related industries, as wetting agents, solubilizing agents, washing agents, foaming agents, emulsifying agents, rewetting agents, dispersing agents, scouring agents, and the like. Since the various surfactant applications of such alcohols are so myriad and categorically nondistinctive, a more conveneint manner of characterizing the surfactants than by their utility is to use a system wherein they are classified as anionic, cationic, amphoteric, or nonionic, depending upon the nature of the ionic charge, if any, of the hydrophilic moiety of the surfactant.
Nonionic-type surfactants to which the subject invention is related have been derived from alcohols by condensing them with alkylene oxides. These, as well as the other surfactant types, may or may not exhibit a sufficient combination of properties so that they can be used beneficially in more than one application.
Regardless of whether a material has a rather wide or narrow range of useful functions, there are some relatively basic and cogent criteria that, in reality, can dictate the suitability and/or acceptability of an alcohol and its surfactant derivatives. For example, a synthetic surfactant may be an excellent detergent and wetter and yet not be biodegradable. This fact would, in effect, bar acceptability of this surfactant by the public and/or the industry.
In like manner, a surfactant may have excellent and varied activities but exist in such a physical state that its use is inconvenient, if not prohibited in many applications. Accordingly, the surfactant may, under conditions normal to its application, undergo gelling and thus become an unusable product. The product may have a prohibitive slow rate of solution in water or have an undesirable cloud point, whereby the value of the surfactant is substantially diminished.
The possession of such attributes as biodegradability, nongelling tendencies, a rapid rate of solution in water, and a desirable cloud point, are, in effect, conditions percedent to the beneficial utilization of a surfactant's basic functions.
Obviously, the worth of an alcohol-derived surfactant is heavily dependent on the characteristics of the alcohol. The basic character of the alcohol determines, to a large extent, whether the alcohol can be satisfactorily and conveniently converted to a surfactant material and whether the surfactant will successfully demonstrate the aforementioned attributes. In summary, the alcohol must be biodegradable and exist in a convenient form, such as in the liquid state at room temperature, in order to enable successful utilization in a wider variety of applications.
To these ends, and in view of recent ecology awareness, alcohols which are essentially linear in nature, such as those derived from natural sources, were necessarily desired by the detergent and related industries for their biodegradable nature. For many practical reasons, including costs, product control, and availability of such natural alcohol sources as fats, oils and waxes, manufacturers have turned to synthesizing alcohols, and their derivatives, which simulate the straight chain character of the naturally occurring products. U.S. Pat. No. 3,598,747 is representative of such an endeavor. Therein, Ziegler-type primary linear alcohols are prepared from trialkylaluminum mixtures made by way of ethylene polymerization, subsequent oxidation, and hydrolysis of the resultant aluminum alkoxides. U.S. Pat. No. 3,391,219 representatively describes the preparation of such trialkylaluminum mixtures and further exemplifies the desire to prepare a highly pure linear alpha-olefin, such as one suitable for subsequent alcohol preparation.
The high linearity of the Ziegler-type alcohols is reported to result in a high degree of biodegradability. The unsuitability and the avoidance of the branched-type alcohols, and their derivatives, in the surfactant area is additionally exemplified in U.S. Pat. Nos. 3,488,384; 3,504,041 and 3,567,784. Notably, a major application for the Ziegler-type alcohols has been in nonionic surfactant production.
Another method now customarily employed for producing similar alcohols is the process comprising reacting linear olefins with carbon monoxide and hydrogen under oxo reaction conditions. Heretofore, however, several companies were employing propylene tetramer feedstocks in the named oxo reaction to produce tridecylalcohol but the branched nature of the alcohol virtually eliminated it as a serious candidate in the surfactant area.
In the present conventional oxo processes, linear alpha-olefin feeds are used whereby a mixture of normal and 2-alkyl branched primary alcohols are produced. Because approximately 30 to 40 wt.%, and greater, of the alcohols have 2 -alkyl branching, the conventional oxo alcohol method has been subjected to criticism. More recently, however, efforts in improving the oxo process have resulted in oxo alcohols having considerably less 2-alkyl branching. U.S. Pat. Nos. 3,239,569 and 3,239,571 illustrate such facts.
It has been reported, such as by the Stanford Research Institute, Linear Higher Alcohols, Report No. 27, Aug. 1967, at pages 3 and 133, that these more recent oxo alcohols having substantially less 2 -alkyl branching are biodegradable because of the occurrence of branching at the favorable 2-position, which type of branching has only a relatively small detrimental effect on the biodegradability of its derivatives. It is evident, therefore, from the above-stated art that branched alcohols for surfactant production are to be otherwise avoided.
Other alcohol types have also been produced by the oxidation of normal paraffins but, unlike those alcohols produced by the ethylene polymerization process and those generally derived from natural origins, are secondary alcohols. The secondary alcohols, unlike the corresponding primary alcohols, in some surfactant applications, such as in the sulfated alcohol area, do not demonstrate the same desired properties. The secondary alcohols have other reported disadvantages.
As will be hereinafter more fully presented, the known alcohols or their surfactant derivatives, lack in varying degrees some of the heretofore detailed criteria that govern the overall suitability and/or acceptability of the alcohol and/or its surfactant derivatives. Accordingly, the heretofore known alcohols do not generally exist in a convenient liquid state and, except for those alcohols below undecanol, and the highly branched alcohols, such as prepared from propylene and butylene trimers, tetramers, and the like, they can be generally characterized as solid or relatively solid materials at or near room temperature. The latter named branched alcohols are unsuitable for surfactant application because of their resistance to biodegradation.
It is clearly evident that there is a definite and acute need for higher molecular weight alcohols that are liquid at room temperature, biodegradable and able to meet the basic standards that regulate whether the useful attributes of the alcohol and its surfactant derivatives can be fully utilized.